1. Field of the Invention
The present invention relates to electrically conductive straps or bars that provide both physical and electrical connections between terminals of electric cells, for forming batteries.
2. Prior Art
Electric batteries are made from electric cells. In the process of making an electric battery, a plurality of electric cells, usually referred to as xe2x80x98dry cellsxe2x80x99, are electrically and physically combined into the electric battery. The design of an electric cell and the quality of the material from which the cell is made usually determines the electric characteristics of the cell. Battery cells or dry cells are manufactured to meet specific specifications, established by the manufacturer. However, although the dry cells produced in the same manufacturing run by the same manufacturer are designed to have the same materials, specifications and electric characteristics, the electric characteristics vary in quality from cell to cell. A process of cell grading is instituted in order to assemble the cells having substantially similar quality electric characteristics. The highest quality electric battery is a battery combined from electric cells having electric characteristics of high and uniform quality.
Heat is the enemy of electric cells and therefore the enemy of electric batteries made from a plurality of cells. It is most desirable to limit and/or keep heat away from battery cells. In order to connect a plurality of cells into a battery, good physical and electrical connections between cells are required. Contemporary cells are made using metal cans and caps because metal is the best conductor of electricity. In order to connect cells into a battery, a cell bar of metal is used. Most assemblers of batteries heat-solder the cell bar to the cell. Some assemblers spot weld the cell bars to cells with multiple spot welds. The cell bar connection process generates a large amount of heat which is conducted to the cell parts. When electrically charging the cells of a battery, the charging process generates heat and with rapid discharge of the battery, such as used in racing electric vehicles, a great amount of heat is generated. The heating of a cell and the retention of heat by the cell degrades the characteristics of the cell and eventually destroys the electrical functions of the cell.
The present invention provides an improved cell bar for electrically and physically bridging or connecting each of two cells, in a plurality of cells, for forming a battery. The improved cell bar is defined by a strip or bar of good to excellent electric conductive material, such as copper or gold, for example, and good to excellent heat conductive characteristics, such as copper or nickel, for example. Preferably, a cell bar is defined by a base or center of copper with an integrated exterior of nickel however, a cell bar of solid copper or another combination of good to excellent electric conductive and heat conductive materials may be used, if desired.
The cell bar includes a heat sink, preferably in the form of a plurality of fingers, connected to and/or integrated into and extending from one or more of the side edges of the cell bar and preferably comprised of good to excellent heat conductive material. One or more holes may be made in the heat sink fingers for increasing the surface of the heat sink for more rapid heat dissipation. The holes may be located in the fingers and/or cell bar, as desired. The heat sink fingers preferably are fabricated from good to excellent heat conductive material and extend from the edge of the side of the cell bar. Preferably, the fingers are spaced from each other for good air circulation and heat dissipation. The heat sink fingers may extend from one side of the cell bar or from both sides of the cell bar and may be uniformly spaced or twisted, for inducing air flow, as desired. The heat sink fingers and/or the cell bar may include one or more holes, the diameter of which is less than the thickness of the finger or cell bar, in which the hole is made, so that the surface of the heat sink function is increased for greater and faster heat dissipation. The heat sink fingers may be extended straight or may be curved. The fingers may be extended at the same angle from the cell bar edge or at different angles, with respect to the horizontal and/or the vertical reference.